copies: teach copies about dirstate.copies
When we're using copies() to find changes between the working directory and
its first parent for diff/status/etc., use dirstate.copies() directly.
This avoids doing a full statwalk for simple diffs (
issue1090) and
removes a special case from the status command.
Make test-bundle-type work on MacOS 10.4.11
head on MacOS Tiger doesn't have a -c option.